On Tue, Oct 13, 2009 at 9:17 AM, Shaul Dar <shauldar@xxxxxxxxx> wrote: > Hi, > > I am running performance simulation against a DB. I want to randomly pull > different records from a large table. However the table has no columns that > hold sequential integer values (1..MAX), i.e. the columns all have "holes" > (due to earlier filtering). Also PG does not have a concept of an > auto-increment pseudo-column like Oracle's "rownum". Any suggestions? If what you're trying to do is emulate a real world app which randomly grabs rows, then you want to setup something ahead of time that has a pseudo random order and not rely on using anything like order by random() limit 1 or anything like that. Easiest way is to do something like: select id into randomizer from maintable order by random(); then use a cursor to fetch from the table to get "random" rows from the real table. -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
